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Mechanical Engineering


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ibrahim1hj last won the day on August 10 2015

ibrahim1hj had the most liked content!

About ibrahim1hj

  • Birthday August 21

Profile Information

  • Gender
  • Location
    United Arab Emirates
  • Present Company
    Hydro Engineering Consultant
  • Designation / Job Title
    Senior Mechanical Engineer
  • Highest Qualification
    Bachelors degree
  • Year of completition
  • Engineering Qualification
    B.S.C Mechanical Engineering Science
  • Year of completition
  • Name of Institute
    Mechanical Engineering - Aleppo University

Contact Methods

  • Skype

More Information

  • Project Undertaken
    Jumeira Lake Tower
  • Achievement /recognition/ Certifications
    JLT, B+G+45

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  1. I want to share with you this important channel https://www.youtube.com/channel/UCnfKeBryyI83hRcfiibPK9Q hope this will help HVAC engineers
  2. My Name is: Ibrahim saleh Occupation: Senior Mechanical Engineer/ (MEP) Project Manager Years of experience: 15-16 Marital Status : Married. No. of Dependents: 4 Location: Dubai- UAE Profile Highlights and summary: Total years of experience almost 15 years (HVAC, Firefighting ,gas, solar system and Plumbing) + Project Management -PMP certificate Equipment selection – Chillers, AHU, FAHU, FCUs, FANS …..etc. Ducting design - HVAC ,HAP load calculation Piping Design – Pipe Stress Analysis; Plumbing (Firefighting, Drainage, Water Supply, & Chilled water) – Fittings Selection and calculation of TDH, Water Tanks, Sump Pits. etc. – Local & International Codes – Project planning, supervision & Team leading. Key Skills: - AutoCAD and Engineering software’s like HAP , Elite , CAESAR II –Pipe Stress Analysis, AutoPipe,Primavera P6,Pump Flow Expert,Matlab7,Photoshop,3d max - Self-motivation, Team-leader, Effective Problems Solving, Good written & oral command skills, Communication Skills - Teamwork and team leading - I.T skills - Technical knowledge and practical problem solving Thanks and hope to keep in contact with this great forum
  3. Dear All, I need this book... Applied Mechatronics (A. Smaili and F. Mrad) If any body has a copy please share , because it is a very useful book for all in this engineering forum Thanks Ibrahim
  4. Differences between Welding, Soldering and BrazingWelding, Soldering and Brazing are the metal joining process. Each type of joining process has its own significance. Type of joining process to be used for joining two parts depends on many factors. In this article I have covered the differences between the joining processes welding, soldering and brazing. S.NoWelding Soldering Brazing 1Welding joints are strongest joints used to bear the load. Strength of the welded portion of joint is usually more than the strength of base metal.Soldering joints are weakest joints out of three. Not meant to bear the load. Use to make electrical contacts generally.Brazing are weaker than welding joints but stronger than soldering joints. This can be used to bear the load up to some extent.2Temperature required is 3800 degree Centigrade in Welding joints.Temperature requirement is up to 450 degree Centigrade in Soldering joints.Temperature may go to 600 degree Centigrade in Brazing joints.3Work piece to be joined need to be heated till their melting point.Heating of the work pieces is not requiredWork pieces are heated but below their melting point.4Mechanical properties of base metal may change at the joint due to heating and cooling.No change in mechanical properties after joining.May change in mechanical properties of joint but it is almost negligible.5Heat cost is involved and high skill level is required.Cost involved and skill requirements are very low.Cost involved and sill required are in between others two.6Heat treatment is generally required to eliminate undesirable effects of welding.No heat treatment is required.No heat treatment is required after brazing.7No preheating of workpiece is required before welding as it is carried out at high temperature.Preheating of workpieces before soldering is good for making good quality joint.Preheating is desirable to make strong joint as brazing is carried out at relatively low temperature. Differences between Welding Soldering and Brazing.pdf
  5. Vapour Absorption System can be compared with Vapour Compression System in 9 aspects, they are energy input, moving part, evaporator pressure, load variation, evaporator exit, coefficient of performance, capacity, refrigerant and lowest temperatures. S.no Aspect Vapour Absorption System Vapour Compression System 1 Energy Input Vapour absorption system takes in low grade energy such as waste heat from furnace, exhaust team or solar heat for its operations. Vapour compression system takes in high grade such as electrical or mechanical energy for its operation of compressor used in the cycle. 2 Moving part It uses a small pump as moving part, which is run by a small motor. It uses a compressor driven by an electric motor or engine. 3 Evaporator pressure It can operate with reduced evaporator pressure, with little decrease in refrigerant capacity. The refrigerant capacity decreases with lowered evaporator pressure. 4 Load variation The performance of vapour absorption system does not change with load variation The performance of vapour compressing system is very poor at partial load. 5 Evaporator exit In vapour absorption system, the liquid refrigerant leaving the evaporator does not put any bad effect on the system except to reduce the refrigerant effect. In a vapour compression system, it is desirable to superheat vapour before leaving the evaporator, so no liquid can enter the compressor. 6 Lowest temperature Since water is used as refrigerant, thus the lowest temperature attained is above 0°C. With cascading, the temperature can be lowered upto -150°C or even less temperature. 7 Coefficient of Performance The COP of the system is poor. The COP of the system is excellent. 8 Capacity It can built in capacities well above 1000 TR. For a single compression system, it is not possible to have a system with more than 1000 TR capacity. 9 Refrigerant Water or ammonia is used as refrigerant. Chloroflourocarbon, hydrochlorofluorocarbon and hydroflorocarbon are used in most of the systems.
  6. What is EDM? A Brief History The acronym EDM is derived from Electrical Discharge Machining. The EDM process we know today started with the observations of Joseph Preistly in 1770. He noticed that electrical discharges had removed material from the electrodes in his experiments. This is also known as electro-discharge erosion. In the 1940's two Soviet researchers, the Lazarenkos', developed a machining process that formed the foundation for modern EDM. Electric Discharge MachiningThe basic EDM process is really quite simple. An electrical spark is created between an electrode and a workpiece. The spark is visible evidence of the flow of electricity. This electric spark produces intense heat with temperatures reaching 8000 to 12000 degrees Celsius, melting almost anything. The spark is very carefully controlled and localized so that it only affects the surface of the material. The EDM process usually does not affect the heat treat below the surface. With wire EDM the spark always takes place in the dielectric of deionized water. The conductivity of the water is carefully controlled making an excellent environment for the EDM process. The water acts as a coolant and flushes away the eroded metal particles. Wire Cutting EDM wire cutting uses a metallic wire to cut a programmed contour in a workpiece. Extrusion dies and blanking punches are very often machined by wire cutting. Cutting is always through the entire workpiece. To start machining it is first necessary to drill a hole in the workpiece or start from the edge. On the machining area, each discharge creates a crater in the workpiece and an impact on the tool. The wire can be inclined, thus making it possible to make parts with taper or with different profiles at the top and bottom. There is never any mechanical contact between the electrode and workpiece (see above). The wire is usually made of brass or stratified copper, and is between 0.1 and 0.3 mm diameter. Depending on the accuracy and surface finish needed, a part will either be one cut or it will be roughed and skimmed. On a one cut the wire ideally passes through a solid part and drops a slug or scrap piece when it is done. This will give adequate accuracy for some jobs, but most of the time, skimming is necessary. A skim cut is where the wire is passed back over the roughed surface again with a lower power setting and low pressure flush. There can be from one to nine skim passes depending on the accuracy and surface finish required. Usually there are just two skim passes. A skim pass can remove as much as 0.002" of material or a as little as 0.0001". During roughing ( i.e. the first cut) the water is forced into the cut at high pressure in order to provide plenty of cooling and eliminate eroded particles as fast as possible. During skimming (accuracy / finish cuts) the water is gently flowed over the burn so as not to deflect the wire.
  7. Efficiency is the percentage of output to input. Like you gave a horse grass to run 100 km, but it ran 50km with that grass, than the horse is 50% efficient. In terms of human hardwork, efficiency has a formula, the one above, but can't be calculated exactly. It's how much output you gave as compared to the input you put and the resources you utilized. Performance on the other hand is a measure of the quality of output. If two horses are given grass to run 100km, but both run 50km. But first runs at double the speed of the second, then they were equally efficient, but the first performed better.
  8. Synthetics are more uniform. Synthetic oils are much more thermally stable as a result of this uniformity. For instance, synthetic oils need lessVI improver additive to keep their viscosity stable. Synthetic oil additives may be higher quality or at least work longer. Synthetics may have better viscosity film strength than petroleum stocks at elevated temperatures (greater than 176°F/80°C). Film strength indicates a lubricant’s ability to occupy the space between two metal surfaces under pressure or heat. This is the fundamental reason for lubrication, to hang in there and do the job. Higher film strength was one of the factors that changed my mind about changing oil. The differences between these types of oils are all in the molecular make-up. Groups I and II are typically classified as mineral base oils, are crude derived and consist mainly of hydrogen and carbon (hydrocarbon) molecules. Group II and III type base stocks help to formulate more economic type semi-synthetic lubricants. These first three base oil groups are widely used in combination with additive packages, ester oils (Group V) and/or Group IV polyalphaolefins in order to formulate semi-synthetic based lubricants. Group III base oils are sometimes considered as synthetic when it is hydro-isomerized. Various petrochemical companies have developed processes involving catalytic conversion of feed stocks under pressure in the presence of hydrogen, into high quality mineral lubricating oil. This process was called hydro-cracking or hydro-isomerization. In 2005 production of gas-to-liquid (GTL) of Group III base stocks began. Even though they are considered a synthetic product, they are still mineral base stocks and counted as the mineral part of all semi-synthetic lubricants. Semi-synthetic oils are blends of mineral oil with no more than 30% synthetic oil. These oils are designed to have many of the benefits of synthetic oil without matching the cost of pure synthetic oil, Mineral oil being a product of nature has lots of different sized molecules in its makeup. Synthetic oil on the other hand, has a very consistent molecule size which gives the synthetic material a controlled structure with predictable properties. Synthetic base stocks are man-made and sophisticated, unlike mineral base oils which are complex mixtures of naturally occurring hydrocarbons.
  9. A graphical method for determining the coefficient of viscosity of newtonian liquids using an oscillating cylinder viscometer
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